As a disk device, a magnetic disk drive includes a housing having a base and a top cover, a rotatable magnetic disk and an actuator for supporting a magnetic head is disposed in the housing. As a method of improving performance of the disk drive, a low density gas such as helium is filled in the housing to reduce the rotational resistance of the magnetic disk and the magnetic head.
In such a magnetic disk drive, the top cover is laser-welded to the base of the housing, so that an enclosed housing is formed with an airtight seal. This laser welding is performed along the entire outer periphery of the top cover. In order to transmit an electric signal of the magnetic head disposed in the housing to the control circuit board disposed outside the device, a connector penetrates the bottom wall of the housing. In a magnetic disk drive filled with a low-density gas, it is preferable to use a hermetic connector as the connector to maintain the airtightness inside the housing.